Netherlands GML Relay TDN Emmen Friday 13th December 2002 Paul Hardy

Laser-Scan and GML UK company - member of the Yeoman Group –in digital mapping since 1974 Long-time members of OpenGIS consortium –Provided primary author of GML-1 spec (AC) –Took part in WMT1 and 2, OWS1.1, 1.2 Implemented SOTF to prototype next generation GML with Change-Only Update and topology Primary supplier of spatial technology to OSGB who are using GML as basis of new MasterMap Contributing topology expertise to GML-3

GML 2.0 in action OS MasterMap Ordnance Survey Crown Copyright

Example of data from GML in LAMPS2 Data courtesy of Topografische Dienst

GML Relay 2002 Data (Gothic LAMPS2)

LSL Approach to Relay Now using 3rd party tools –to let us focus on our key technologies Emphasis of this demo is on –interoperability –topological structure Looking forward to GML-3

GML Relay 2002 Data (MapInfo/Oracle/Radius)

Topology Mathematical concept of spatial structure: “Characteristics of geometry which do not change when the coordinate space is deformed” Express explicit geometric relationships –connects to, touches, adjacent to, within Topology Primitives –Node, Edge, Face, Solid Should be present in most GIS data –Shared edges between land polygons –connected networks of roads

Shared Edges, Shared Nodes

Radius Topology Enterprises and agencies want to hold business and spatial data in one database Radius Topology is the server-side topology manager for Oracle9i Enhances spatial data quality and query performance. Calculates and stores the topology in tables, using standard ISO model. Based on proven topology engine from Laser- Scan Gothic object database and toolkit

Today’s LSL Relay Radius Tables Radius Triggers Radius Topology Engine Business data Spatial data Oracle9i SQL OCI Intergraph GeoMedia Snowflake Go Loader GML MapInfo

Go Loader

Radius Topology Configuration Manager

Radius Topology Classes and Priorities

Most GIS data is Spaghetti gaps slivers under- shoots overshoots … data faults affect query quality

Snapping and Topology...or...

Rules: Node Formation Edge Split EdgeShare NodeNode Split Edge

Priorities: Gold Standard Data - High priority feature - Low priority feature Before After

Face Topology - Containment Need to find all features on the lake

Face Encoding Face records all adjacency and containment through encoding for boundary and isolated

GML 2.0 and 3.0 Geometry GML 2.0 provides for: –Simple geometry types Point/MultiPoint LineString/MultiLineString Polygon/MultiPolygon –Boundary Types LinearRing –Simple linear interpolation –Coordinates up to 3D GML 3.0 geometry –from ISO –superset of GML 2.0 –Geometric primitives up to 3D volumetric solids –composites (line/arc) –splines, conics, tins –curves and surfaces. Topology model

GML 2.0 Geometry Schema

AS Topic 1/ISO Geometry GML 2.0

GML-3 Topology Edge

Spatial Query Performance “Find all districts which touch or are covered by the county of Cambridgeshire (UK)”

Spatial Query Comparison Oracle Spatial Optimised Radius Topology inside Oracle Spatial Features found per second At Least 400 times faster !

Error in Topology

Edges & Nodes

Edit of Edge modifies both polygons Edges & Nodes created dynamically

Export to GML via GeoMedia

Resultant XML (in MSIE)

Resultant XSD Schema

Round trip the exported GML (with faulty projection!)

Is The Way Ahead ! GML with Topology